Google yesterday claimed that websites running Microsoft's web server software are twice as likely to be hosting malicious code as other websites. In reaching this conclusion, Google's Anti-Malware team last month looked at 70,000 web domains that were either distributing malware or hosting attack code.

"Compared to our sample of servers across the internet, Microsoft IIS features twice as often as a malware-distributing server," wrote Google's Nagendra Modadugu in a blog.

Google actually found an equal number of Apache and IIS websites hosting malicious software, but because there are so many more sites hosted by Apache servers (66 percent versus Microsoft's 23 percent) malicious sites make up a much larger percentage of all IIS servers. Together, IIS (Internet Information Services) and Apache servers host about 89 percent of all websites, but collectively they're responsible for 98 percent of all web-based malware.

Modadugu didn't draw any conclusions about whether this means that Microsoft servers are more likely to be hacked.

"It is important to note that while many servers serve malware as a result of a server compromise... some servers are configured to serve up exploits by their administrators," Modadugu wrote.

Google also found that the malware server of choice varied from region to region. In China and South Korea, for example, the majority of malicious websites are running IIS. In the US, Russia, and Germany, however, Apache is the predominant malware server.

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